Sevim Isik

DNA topoisomerase IIβ (topo IIβ) is a nuclear enzyme that regulates DNA topology and gene expression, especially in post-mitotic cells such as neurons. Although its roles in neural development and transcriptional control are well-established, its involvement in neuroinflammatory processes is still to be investigated. This study aims to investigate whether topo IIβ modulates inflammatory responses in human microglial HMC3 cells under immune-stimulated conditions, considering that microglial cells are pivotal mediators of neuroinflammation in the central nervous system (CNS). Inflammation was induced using lipopolysaccharide (LPS), interferon-gamma (IFNγ), Adenosine triphosphate (ATP), whereas topo IIβ expression was modulated by overexpression and siRNA-mediated silencing. Western blot analysis demonstrated that LPS, IFNγ, and ATP stimulation did not alter the endogenous topo IIβ protein levels, indicating that its protein levels are stable under inflammatory conditions. Analysis of cytokine release indicated that topo IIβ overexpression decreased the release of key proinflammatory cytokines, suggesting an anti-inflammatory role. Conversely, the silencing of topo IIβ resulted in increased cytokine release, suggesting that topo IIβ typically functions to mitigate microglial inflammatory responses. Significantly, treatment with Lipofectamine™ 3000 alone increased cytokine release, indicating an intrinsic immunostimulatory impact of the transfection reagent. Collectively, these findings reveal an unacknowledged function of topo IIβ in attenuating neuroinflammatory signaling in microglia and underscore the necessity for careful interpretation of cytokine data when transfection reagents are present. Topo IIβ may represent a novel therapeutic target for modulating microglial activation in neuroinflammatory diseases.

Neuroinflammation is central to the progression of neurodegenerative diseases (NDs), with microglia contributing through the release of pro-inflammatory and oxidative mediators. Although quercetin (Que) possesses potent anti-inflammatory and antioxidant properties, its clinical application is limited by poor solubility and bioavailability. Umbilical cord mesenchymal stem cells (UC-MSCs)-derived exosomes (Exo) offer a promising delivery system to enhance Que efficacy. This study investigated the anti-inflammatory effects of Que-loaded Exo (Que-Exo) using an in vitro neuroinflammation model. Exo were isolated from UC-MSC-conditioned media via ultracentrifugation and loaded with Que through sonication. Characterization of Exo and Que-Exo was performed using dynamic light scattering, zeta potential analysis, transmission electron microscopy, and western blotting. In vitro release and cellular uptake studies assessed Que-Exo release profiles and their internalization by HMC3 microglial cells. Neuroinflammation was induced in HMC3 cells using lipopolysaccharide (LPS). The effects of Que-Exo on pro-inflammatory cytokine and enzyme expression, nitric oxide (NO) production, and inflammatory signaling pathways were evaluated using flow cytometry, the Griess assay, and western blotting. In vitro release from Que-Exo demonstrated improved stability and controlled delivery, while fluorescence imaging confirmed efficient uptake of Que-Exo by HMC3 cells. Mechanistically, Que-Exo inhibited NF-κB nuclear translocation, a key regulator of pro-inflammatory mediator transcription. Que-Exo pretreatment significantly reduced TNF-α, IL-6, iNOS, and COX-2 expression and suppressed NO synthesis in LPS-stimulated cells. Overall, Que-Exo exhibited superior anti-inflammatory activity compared to Exo and free Que, highlighting the synergistic effect of exosomal delivery in enhancing Que bioavailability and therapeutic efficacy against neuroinflammation. Graphical Abstract

Aging is considered the most important risk factor for neurodegenerative diseases such as Alzheimer's, Parkinson's and Huntington's diseases. Moreover, it is interpreted that irregular neurogenesis may also be one of the causes of neurodegenerative diseases. The brain-derived neurotrophic factor signal, a growth factor known to play an important role in the development and plasticity of the brain by promoting neurogenesis, synaptic plasticity and cell survival, decreases in the brain with aging and may be the cause of neurodegenerative diseases. Intermittent fasting or calorie restriction, a nutritional method, increases brain-derived neurotrophic factor expression in various regions of the human and rodent brain. This brings to mind the question of whether nutritional methods such as intermittent fasting and calorie restriction may play a role in preventing neurodegenerative diseases. Based on this, it has been investigated how these nutritional methods trigger adult hippocampal neurogenesis by signaling brain-derived neurotrophic factor and how they affect the brain's resistance to aging by causing changes in the hippocampus area of the brain that controls learning, memory and mood. Significant evidence obtained from human and animal studies reveals that brain-derived neurotrophic factor signaling plays a role in the beneficial effects of intermittent fasting and calorie restriction on brain aging and that this is important in terms of promising a functional result in preventing neurodegenerative diseases.

Alzheimer’s disease is the leading cause of dementia worldwide. The neuroprotective impact of essential oil from Apium graveolens L. leaves collected in Türkiye was investigated. The celery leaves oil was extracted by hydrodistillation, and its chemical constituents were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS), followed by anti-beta amyloid cytotoxicity, anticholinesterase, anti-inflammatory, and antioxidant potential. The main essential oil constituents were then tested for their ability to inhibit AChE and BuChE using molecular docking studies. From the essential oil yield (0.1% (w/w)), fourteen components were identified, with l-limonene accounting for the majority (35.4%), followed by cis-ocimene (21.47 %), umbellulone (10.98 %), and enzenemethanol, α-ethyl (10.75%). The oil exhibited significant neuroprotection against Aβ1-42 at a concentration of 1:2x104 dilution from the stock solution (0.1 µl/mL) on SH-SY5Y cells. This concentration increased the viability of cells from 67% to 85.84% against 15 μM Aβ1-42 toxicity. The oil exhibited AChE and BuChE inhibitory potential with (IC50: 22 and 43 µg/mL, respectively). The oil has shown significant antioxidant ability and inhibited COX-1 and COX-2. In all instances, the docking scores for AChE are notably higher than those for BuChE across all tested compounds. Among the investigated test compounds, 1-Limonene exhibits the highest docking scores. In conclusion, the neuroprotective effects of oil highlight its potential for creating novel drugs for AD.

The study explores the interaction between topoisomerase IIβ (topo IIβ) and α-synuclein aggregation in Parkinson’s disease (PD) using an in vitro model overexpressing A53T mutant α-synuclein, revealing key pathological features. The overexpression of A53T mutant α-synuclein was associated with impaired neuronal differentiation, accompanied by delayed neurite outgrowth and reduced levels of MAP2 and NF-L. Transcriptomic study during differentiation revealed substantial gene expression changes, with 57 of 84 PD-associated genes exhibiting differential regulation on days 8 and 12. Dopaminergic markers like TH, BDNF, NR4A2 (Nurr1), PINK1, and SYNGR3 were notably upregulated in differentiated cells, whereas A53T mutant α-synuclein overexpression was associated with significant downregulation of 22 genes associated with PD, including TH, NR4A2, BDNF, and PINK1, suggesting alterations in neuroprotective signaling pathways. Topo IIβ expression diminished during differentiation in the presence of pathogenic α-synuclein and was associated with changes in the proposed topo IIβ-Nurr1 regulatory axis potentially contributing to early neurodevelopmental abnormalities and dopaminergic vulnerability observed in PD.

Neuroinflammation is a central factor in many neurodegenerative diseases, making it an important target for novel treatments. This study compares the effects of organic red onion–derived materials, particularly crude extract and exosome-like nanovesicles (RO-ELNs), on neuroinflammation in the human microglia HMC3 cell line. Red onions are abundant in neuroprotective phytochemicals, primarily quercetin and anthocyanin constituents. The non-cytotoxic RO-ELNs purified through ultracentrifugation, along with their corresponding ethanolic extract, showed that they contain inherited phytopharmaceutical compounds from their parent source. Despite RO-ELNs having lower metabolite concentrations relative to the extract, their therapeutic value is mostly attributed to their lipids and other components. Both treatments engage similar biological pathways yet demonstrate contrasting time-dependent anti-neuroinflammatory and antioxidant effects by suppressing NLRP3 inflammasome components (NLRP3, IL-1β) and critical inflammatory markers (COX-2, phospho-NF-κB, ROS, IL-6, TNF-α) during acute inflammation. Nevertheless, the extract showed restricted effectiveness in prolonged inflammation or at longer incubation times owing to its poor bioavailability. Conversely, RO-ELNs showed a robust and lasting effect due to their lipid bilayer, facilitating gradual uptake and extended retention within target microglia, with uptake escalating from 20 to 70% over 24 to 72 h compared to control. This study uniquely investigates the time-dependent anti-inflammatory and antioxidant actions of red onion–derived ELNs and extract across acute and prolonged phases of neuroinflammation, suggesting RO-ELNs as a promising nanosized approach for neuroinflammation prevention. Graphical Abstract

Neuroinflammation in the pathogenesis of neurodegenerative diseases is still a subject of discussion, as it might be either the cause or the result of neurodegeneration. Misfolded or improperly aggregated α-synuclein in Parkinson’s Disease, can cause inflammatory responses, indicating a mechanistic relationship between α-synuclein pathology and neuroinflammation. The aim of this study was to investigate the role of DNA topoisomerase IIβ, the key player of DNA topology, in the neuroinflammation process in an age-dependent transgenic Parkinson’s Disease mouse model overexpressing the A53T mutant α-synuclein. In this study, transgenic and control mice were bred in three age groups as early (3 months), mid (8 months), and late (12 months) disease stages. Behavioral experiments were carried out to compare the age-related cognitive and motor coordination functions. Cytokine levels in the serum and protein expression levels in the dissected brain were analyzed by both western blot and immunofluorescence staining. A decline was observed in the cognitive and motor coordination functions depending on age. Disease-related markers at protein level appeared even in the early stage, and accordingly, a significant increase was observed in inflammatory markers and cytokine levels compared to control. DNA Topoisomerase IIβ and Nurr1 levels decreased in transgenic mice, especially more dramatically in the early stage. The combined effect of reduced Nurr1 and DNA Topoisomerase IIβ, along with increased inflammation, may provide a better understanding of the pathogenesis of Parkinson’s Disease at early-stage and requires for further investigation of the potential alterations in topo IIβ as an intervention strategy for this disease.

Aim: This review provides a systematic evaluation of 94 stem cell clinical trials to treat neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease. Methods: Data were collected from using relevant search terms, focusing exclusively on stem cell therapy. Of the 8000+ participants in these trials, nearly 70% were enrolled in AD‐related studies. Only three Phase 3 studies were conducted, and most trials were in the early phases (Phases 1 and 2). Mesenchymal stem cells, neural stem cells, induced pluripotent stem cells, and embryonic stem cells are used the most to treat neurodegenerative diseases. This review also explores the emerging fields of preclinical and clinical investigations of stem cell‐derived exosome‐based therapies for neurodegenerative diseases. Results: Exosomes can cross the blood–brain barrier to deliver therapeutic molecules directly to the brain, offering a less invasive alternative to stem cell transplantation. Mesenchymal stem cell‐derived exosomes, in particular, have demonstrated significant potential in preclinical models by reducing neuroinflammation, oxidative stress, and promoting neuronal regeneration. Additionally, recent advances in exosome engineering, including surface modifications, therapeutic agent loading, and transgenic modifications, have improved targeting, stability, blood–brain barrier delivery, and neural cell interactions, enabling targeted and effective treatment. Exosome‐based therapies are in the preliminary phases of clinical investigation, with only three clinical trials. Conclusion: Given the increasing interest in exosome therapy, clinical investigations are expected to increase. This growth will be driven by ongoing advancements in exosome technology, a deeper understanding of their therapeutic potential, and escalating demand for innovative treatment strategies for neurodegenerative diseases.